fix(auth): initialize signer to 0 bytes (#32)

move/axelar_gateway/sources/types/weighted_signer.move

@@ -1,9 +1,17 @@
 module axelar_gateway::weighted_signer {
     use sui::bcs::BCS;
 
+    // ---------
+    // Constants
+    // ---------
+
+    /// Length of a public key
+    const PUBKEY_LENGTH: u64 = 33;
+
     // -----
     // Types
     // -----
+
     public struct WeightedSigner has copy, drop, store {
         pubkey: vector<u8>,
         weight: u128,
@@ -20,21 +28,26 @@ module axelar_gateway::weighted_signer {
     // ------
     // Errors
     // ------
+
     const EInvalidPubkeyLength: u64 = 0;
 
     // -----------------
     // Package Functions
     // -----------------
+
     public(package) fun new(pubkey: vector<u8>, weight: u128): WeightedSigner {
-        assert!(pubkey.length() == 33, EInvalidPubkeyLength);
+        assert!(pubkey.length() == PUBKEY_LENGTH, EInvalidPubkeyLength);
 
         WeightedSigner { pubkey, weight }
     }
 
-    /// zero pubkey
+    /// Empty weighted signer
     public(package) fun default(): WeightedSigner {
+        let mut pubkey = @0x0.to_bytes();
+        pubkey.push_back(0);
+
         WeightedSigner {
-            pubkey: vector[],
+            pubkey,
             weight: 0,
         }
     }
@@ -48,10 +61,9 @@ module axelar_gateway::weighted_signer {
 
     /// Check if self.signer is less than other.signer as bytes
     public(package) fun lt(self: &WeightedSigner, other: &WeightedSigner): bool {
-        let length = 33;
         let mut i = 0;
 
-        while (i < length) {
+        while (i < PUBKEY_LENGTH) {
             if (self.pubkey[i] < other.pubkey[i]) {
                 return true
             } else if (self.pubkey[i] > other.pubkey[i]) {
@@ -63,4 +75,22 @@ module axelar_gateway::weighted_signer {
 
         false
     }
+
+    // -----
+    // Tests
+    // -----
+
+    #[test]
+    fun test_default() {
+        let signer = default();
+
+        assert!(signer.weight == 0, 0);
+        assert!(signer.pubkey.length() == PUBKEY_LENGTH, 1);
+
+        let mut i = 0;
+        while (i < PUBKEY_LENGTH) {
+            assert!(signer.pubkey[i] == 0, 2);
+            i = i + 1;
+        }
+    }
 }